Idle talk, chatter.

1

1857.  Whenever he presents himself in the presence of the Saints, and attempts to entertain them or amuse them with his chin-music, they expect that he will say something funny.—George A. Smith at the Bowery, Salt Lake City, Aug. 2: ‘Journal of Discourses,’ v. 101.

2

1872.  The thing I’m on now is to roust out somebody to jerk a little chin-music for us and waltz him through handsome.—Mark Twain, ‘Roughing It,’ ch. vi. (N.E.D.)

3